Well it's a somewhat longer story. I have some code to interface via the serial lines. And I want to do that on Windows and Linux. So far so good. Now my code for interfacing to the serial lines works fine on Windows. But it fails on Linux here's the debug.log from Pharo: THERE_BE_DRAGONS_HERE PrimitiveFailed: primitive #primWritePortByName:from:startingAt:count: in SerialPort(#'/dev/ttyUSB0', 9600 baud, 8 bits, 1 stopbits, no parity) failed 11 February 2012 10:56:40 am VM: unix - i686 - linux-gnu - Croquet Closure Cog VM [CoInterpreter VMMaker.oscog-eem.78] Image: Pharo1.3 [Latest update: #13320] SerialPort(Object)>>primitiveFailed: Receiver: SerialPort(#'/dev/ttyUSB0', 9600 baud, 8 bits, 1 stopbits, no parity) Arguments and temporary variables: selector: #primWritePortByName:from:startingAt:count: Receiver's instance variables: port: '/dev/ttyUSB0' baudRate: 9600 stopBitsType: 1 parityType: 0 dataBits: 8 outputFlowControlType: 0 inputFlowControlType: 0 xOnByte: 19 xOffByte: 24 SerialPort(Object)>>primitiveFailed Receiver: SerialPort(#'/dev/ttyUSB0', 9600 baud, 8 bits, 1 stopbits, no parity) Arguments and temporary variables: Receiver's instance variables: port: '/dev/ttyUSB0' baudRate: 9600 stopBitsType: 1 parityType: 0 dataBits: 8 outputFlowControlType: 0 inputFlowControlType: 0 xOnByte: 19 xOffByte: 24 Where do I start or how do I start to solve this error? Regards Friedrich -- Q-Software Solutions GmbH; Sitz: Bruchsal; Registergericht: Mannheim Registriernummer: HRB232138; Geschaeftsfuehrer: Friedrich Dominicus